Hey there!

Let’s talk about probability. When you’re in Year 7, you’ll often hear the words "and" and "or". These words help us learn how to combine different probabilities.

Let’s look at some simple examples to make it easier to understand!

Example of 'And' Probability

Imagine this: You’re picking a card from a regular deck of 52 cards.

If you want to know the chance of drawing a heart and that heart being the queen, you need to think about both things happening at the same time.

Here’s how to figure it out:

1. There are 13 hearts in a deck.
2. There are 4 queens in total (one for each suit).
3. There is 1 card that is both a heart and a queen (the Queen of Hearts).

So, the probability of drawing a queen and it being a heart is:

$P(\text{Queen and Heart}) = \frac{\text{Number of Queen of Hearts}}{\text{Total number of cards}} = \frac{1}{52}$

Example of 'Or' Probability

Now, let’s say you want a snack from a box with 5 chocolate bars and 3 packets of crisps.

You want to find out the chance of picking either a chocolate bar or a packet of crisps.

Here’s the breakdown:

1. The total number of snacks is 5 + 3 = 8.
2. In Set A (chocolate bars), there are 5.
3. In Set B (crisps), there are 3.

To find the probability of getting either a chocolate bar or a crisp, we add up the chances of each option:

$P(\text{Chocolate bar or Crisp}) = P(\text{Chocolate bar}) + P(\text{Crisp}) = \frac{5}{8} + \frac{3}{8} = 1$

In Summary

• 'And' Probability is when both events happen at the same time, like drawing a specific card.
• 'Or' Probability is when either event can happen, like choosing a snack from a mixed box.

I hope these examples help you understand 'and' and 'or' probabilities better! Remember, it's all about thinking through the possibilities. Happy studying!